In the field of integrated optics, there may be a need to use a switch, e.g., to route signals and/or to add or subtract signal-carrying lines.
U.S. Pat. No. 5,915,050 to P. Russell, et al describes an optical device including an optical fiber directional coupler supporting at least two possible electromagnetic transmission modes. An acousto-optic effect is used to create a spatial periodic perturbation, which allows power transfer between the transmission modes.
U.S. Pat. No. 5,418,868 to Cohen et al describes a thermally active optical device based on a Mach Zehnder Interferometer (MZI) optically coupled to an adiabatic 3 dB input coupler and an adiabatic 3 dB output coupler. One arm of the MZI includes a thermo-optical phase shifter. The thermo-optical phase shifter may be used to control the distribution of transmitted light at the output of the device.
A dynamic device is defined as a device in which an optical property of the device may be altered, e.g., the device may be turned on/off and/or a refractive index of the device may be changed. A passive device is defined as a device in which all optical properties are pre-determined and depend only on a power distribution of a light injected into the device.